Toroidal induction coil



Jan. 22, 1929. I 4 1,699,609

4 P H. DAVIS TOROIDAL INDUCTION COIL Filed June 22, 1925 2 Sheets-Sheet1 f j My QQJLQ- Jan. 22, I929.

P. H. DAVIS TOROIDAL INDUCTION COIL 2 Sheets-Sheet 2 Filed June 22, 1925Patented Jan. 22, 1929.

UNITED STATES PATENT OFFICE.

PAUL H. DAVIS, OF CHICAGO, ILLINOIS, ASSIGNOR OF ONE-HALF TO JOHNELLIOTT JENKINS, OFCIHICAGO, ILLINOIS.

TOBOIDAL INDUCTION COIL.

Application filed June 22, 1925. Serial No. 38,710.

This invention relates in general to inductioncoils and moreparticularly to induction coils of toroidal form and adapted for use inradio apparatus or the like for transferr' currents from one circuit toanother by inductance, and as an incident thereto and upon occasion, thecurrent may also be transformed to a higher or lower E. M. F.

A principal object of the invention is to provide such a device that iscontrollable to vary the coupling between windings and thereby controlthe inductance. Devices of this character provided heretofore have beenof the fixed type and no variation of coupling has been possible.

Another important object is to provide a variable inductance transformerhaving a confined and closed field. A coil of this type is particularlyadapted for use as an oscillator or radio frequency transformer in radioapparatus, as the output may be varied at will and no external field isgenerated that would disturb other apparatus in the intermediatevicinity.

Another important object is to provide such a device that may beeconomically manufactured, that is rigid and durable, and that may bemounted as a unit and readily connected into various electricalcircuits.

Numerous other objects and advantages of the invention will be apparentas it is better understood from the following description, which, takenin connection with the accom panying drawings, discloses a preferredembodimentthereof.

Referring to the drawings,

Figure l is a side elevation of a device embodying my invention;

Fig. 2 is a section taken substantially on line 22 in Fig. 1;

Fig. 3 is a section line 33 in Fig. 1;

Fig; 4 is a side elevation of the parts shown in Fig. 3 and partlybroken away to show taken substantially on details of construction;

Fig. 5 is a section taken substantially on line 5-5 in Fig. 4;

Fig. 6 is a section taken substantially on line 6-6 in F ig.4 withcertain parts omitted;

Fig. 7 is a perspective view showing a detail of construction;

Fig. 8 is a perspective view showing a. detail of construction; and

Fig. 9 is a perspective view showing a detail of construction.

To illustrate my invention, I have shown a coil adapted for use as aradio frequency transformer having a fixed winding 11 and rotatable orvariable windings 12 and 13, an internal spacing member 14 to which thevarious windings may be secured, a confining strip 15 for securing thefixed winding 11 to the internal spacing member 14 and brackets 16 toprovide a bearing for the rotatable windings 12 and 13. 5

The fixed winding 11 is preferably of a toroidal form, the separatewindings of which may be substantially in the form of a figure 8 toprovide two adjacent and parallel fields '17 and 18. Current maybepassed through hand, or a clockwise or counter-clockwise The internalspacing member 14: is or may 35 be of any suitable insulating material,and is preferably solid, as shown, having a V shaped rim 21 and a pairof shoulders 22 and 23 adjacent the rim and is preferably cut away at 24to providea bearing for one or more brackets 16. The brackets 16 may beof any suitable non-magnetic metal and are preferably substantially Ushaped having a pair of flanges 25 extending downwardly on each side ofthe base 26, which may be Se 5 cured to the internal spacing member 14by any suitable means and are preferably apertured as at 27 to receive abolt 28 which may also be provided with a knurled nut 29 and used as abinding post. The upper end of a leg 31 of the brackets 16 is bent at.right angles to provide a leg 32 to which the strip may be made of anyinsulating material and an obtuse angle.

is preferably depressed intermediate its edges to provide a pair ofshoulders 35 and 36 for locating the fixed winding 11, and is secured atits opposite ends to legs 32 of the brackets 16 by a screw 37, which maybe suitably insulated f om the leg 32 of the brackets 16 to providebinding posts for the' wind ing 11.

Rotatable windings 12 and 13 are wound in accordance with the fixedwinding, and in the present instance, in cross section are substantiallyin the form ofa figure 8. These coils are preferably mounted by means'ofangle plates 41, 42, 43 and 44, which may be of any suitable insulatingmaterial and are bent along a line 45 to an angle in accordance with thespacing of the coils. In the present instance, I have shown two of theplates bent to an acute angle and two bent to The length and width ofthese angle plates are determined by the size of the winding. Each ofthese plates isprovided with an extension 46 at each end, which ispreferably integral with the plate, located at the line of bend and ofsufficient length to extend through the brackets to provide a bearing;The plates 41, 42, 43 and 44 arepositioned' within the coil as shown(Figs. 4, and 6) and the extensions 46 at either end :7 thereof aregathered together,and a collar periphery 47 is tightly pressed thereoverwhich provides a cylindrical bearing 48 and secures the windings ofthecoil in fixed relation. A knurled disk 49 which is apertured at 51 toprovide .a press fit is pressed over the bearing 48 at one side of thecoil. This disk is preferably partly cut away to provide spokes andopeningstherebetween, and is marked with suitablecharacters or indiciaadjacent the thereof. Lead wires 52 are suitablysecured to the ends ofthe windings of the rotatable coils and are of sufiicient length toextend to the binding posts 29, 53 and 54,

which may be secured to the internal spacing" member 14.

The rotatable windings are rotatably supported in the legs 31 and 33ofthe U shaped members, the bearings 48 extending through apertures 55.,Washers 56 are provided and positioned over the bearings and disposedbe tween the legsofthe U shaped brackets of the rotatable winding toreduce friction imposed by the legs 31 and 33, which are preferablyformed to fiexoslightly toward each other.

The internal spacing member 14 may be apertured as at 57 to facilitateattaching the coil to a suitable support.

In operation, in a coil such as described, which is a radio frequencytransformer having a fixed secondary 11, rotatable primary 13 and also arotatable tickler coil 12, current of the rotatable winding, out-ofalignment or coupling with the'fields of the -fixed winding,

any intermediate position giving a degree of couplin rotation of therotatable windings, and thus the;degree ofinductance may be varied atwill by rotating the rotatable winding. The ticklercoil or secondrotatable winding functions in a like manner and it is believed thefunction thereof in radio apparatus isfully understood and need notfurther be described.

While I have shown and described a radio frequency transformer having atickler or feedback coil, it will be understood that this type of coilmay be used without the feedback, it may be used with a fixed primary, asecondary and rotatable feed-back; and may I be used as either anoscillator for modulating or amplifying in any of theabove combinationsor the like. s

It is thought that the invention and many of the rotatinaccordance withthe degree of V of its attendant advantages will be understood from theforegoing description, and it will be apparent that various changes maybe made in the form, construction and arrangement of the parts without.departing from the spiritand scope of the invention or sacrificing allof its material advantages, thev form hereinbefore described beingmerely preferred embodiment thereof.

Iclaim: i w 1 1. A toroidal induction coil, comprising, a fixed windingincluding a major portion of the toroidal form, a rotatable windingdisposed within the toroidal form and between the ends of said fixedwinding,'internal spacing means, means for confining said fixed windingagainst said internal spacing means, and means for securing the parts infixed relation and provldingabearmg for said rotatable winding.

2. A toroidal induction coil, comprising,- a

fixed winding including a major portion of the toroidal form, aplurality of rotatable windings disposed within the toroidal form andbetween the ends of said fixed winding,

internal spacing means, means for confining said fixed winding aga nstsaid internal spacing means, and means for securing the parts in fixedrelation and providing bearings for said plurality of rotatablewindings.

3. A toroidal induction coil, comprising a fixed winding having adjacentand parallel toroidal fields, a rotatable winding having adjacent andparallel fields disposed within V the toroidal form, and means forsupporting said fixed andsaid movable W nding in operative relation,said movablewmding being 5 with.

movable between positions wherein the fields thereof will be inaccordance with the fields of said fixed winding and positions whereinsaid fields will not be in accordance there- 4. A toroidal inductioncoil comprising a fixed Winding suitably mounted and arranged to enerateadjacent and parallel toroidal fields, and a plurality of rotatablecoils disposed within the toroidal form and in substantial prolongationthereof, said rotatable coils being adjustable relative to themselvesand to the fixed winding.

PAUL H; DAVIS.

